JP 2004-329355A to Sugiyama, et al. (Patent Reference 1) discloses a stereoscopic variable image-printed jigsaw puzzle which is characterized in that the jigsaw puzzle pieces are made of 0.2-3.0 mm-thick lenticular lens having a lens pitch of 20-150 lines/inch, and the beads are set in a surface of a board case on which a pattern whose image is resolved at the same pitch to the lens pitch of said lenticular lens is formed, to configure the stereoscopic, variable image; and a method for making the same.
JP 2004-329355A (Patent Reference 1) also discloses a stereoscopic, variable print jigsaw puzzle in which each jigsaw puzzle piece is formed of a dot lens sheet, and the pieces are set in a surface of a board case in which a pattern comprising a halftone printed portion is formed, to configure a stereoscopic, variable image, characterized in that the line number (m) of the halftone printed portion and the line number (n) of the dot lens sheet satisfy the following relationshipn=50−150, m=(½− 3/2)×n, m≠n, and a method for making the same.
However, this Patent Reference 1 lacks a disclosure concerning provision of a stereoscopic image in a retroreflective sheeting which retroreflects light. The jigsaw puzzle of Patent Reference 2 is said to have high visual effect and design quality, giving a feeling of achievement and satisfaction of having completed the puzzle, and increased entertainability. The Reference also states that the jigsaw puzzle pieces as combined show high decorative effect. The use of its virtual image for tamper prevention, however, is not disclosed.
JP Hei 10(1998)-035083A (Patent Reference 2) discloses a stipple pattern decorative article utilizing moire effect, which is made by printing on a surface of a transparent substrate hemispherical or circular arced planoconvex lens-formed focusing elements regularly at a constant, fine pitch; also printing on the back of the transparent substrate picture elements of identical shape, which are arrayed in identical manner, with those of the planoconvex lens-formed focusing elements, or picture elements of different shape which however are arrayed in identical manner, with the planoconvex lens-formed condensing elements, at their crossing angles shifted from those of the planoconvex lens-formed condensing elements on the front surface; or printing on a substrate different from the transparent substrate colored picture elements of identical or different shape from that of the planoconvex lens-formed focusing elements, which are arrayed in the identical manner with the planoconvex lens-formed focusing elements, and sticking the substrata to the transparent substrate, shifting their crossing angle.
Patent Reference 2, however, does not contain any disclosure relating to setting up stereoscopic images in retroreflective sheeting which retroreflects light. Although it states that the decoration of Patent Reference 2 is interesting to watch and hence can be utilized for display plates or printed matters, it is silent on use of the virtual images for tamper prevention.
Conventionally, retroreflective sheeting which reflects incident light toward the light source is well known. The retroreflective sheeting has been widely utilized in the fields making use of its retroreflectivity, such as of signs including road signs and construction signs; number plates on vehicles such as automobiles or motorcycles; safety goods such as clothing and life preservers; marking on signboards; various types of certification stickers or reflective plates and the like. In particular, adoption of retroreflective sheeting for various kinds of number plates or certification stickers is increasing in these years.
As such reflective sheeting, total internal reflection type cube-corner retroreflective sheeting, specular reflection type cube-corner retroreflecive sheeting, encapsulated lens type retroreflective sheeting, enclosed lens type retroreflective sheeting and open lens type retroreflective sheeting are well known.
Total internal reflection type cube-corner retroreflective sheeting is described, for example, in U.S. Pat. No. 3,417,959 to Schultz (Patent Reference), JP2001-264525 to Mimura (Patent Reference 4, corres. to U.S. Pat. No. 6,318,866.
Specular reflection type cube-corner retroreflective sheeting is described, for example, in JP Public Announcement Hei 8(1996)-510415A to Roland (Patent Reference 5, corres. to U.S. Pat. No. 5,376,431 and WO 01/057560 to Mimura, et al. (Patent Reference 6, corres. to U.S. Pat. No. 6,817,724).
Examples of encapsulated lens type retroreflective sheeting include those described in JP Sho 40 (1965)-007870B to McKenzie (Patent Reference 7, corres. to U.S. Pat. No. 3,190,178), JP Sho 52 (1977)-110592A to McGrath (Patent Reference 7, corres. to U.S. Pat. No. 4,025,159) and JP Sho 62 (1987)-121043A to Bailey, et al. (Patent Reference 9, corres. to U.S. Pat. No. 5,064,272).
Examples of enclosed lens type retroreflective sheeting are described in JP Sho 59(1984)-071848A to Belisle (Patent Reference 10, corres. to U.S. Pat. Nos. 4,721,694 and 4,725,494).
These patents on retroreflective sheetings, however, contain no description relating to incorporation of printed image in retroreflective sheeting or to the use of whereby obtained stereoscopic image for tamper prevention.
[Patent Reference 1] JP 2004-329355A
[Patent Reference 2] JP Hei 10(1998)-035083A
[Patent Reference 3] U.S. Pat. No. 3,417,959
[Patent Reference 4] JP2001-264525
[Patent Reference 5] JP Public Announcement Hei 8(1996)-510415A
[Patent Reference 6] WO 01/057560
[Patent Reference 7] JP Sho 40(1965)-007870B
[Patent Reference 8] JP Sho 52(1977)-110592A
[Patent Reference 9] JP Sho 62(1987)-121043A
[Patent Reference 10] JP Sho 59(1984)-071848A